Lean codes are usually caused by vacuum leaks (i.e. too much air) so you'd be better off checking for those first.
However, clogged injectors or a fuel pump that doesn't like the cold anymore (i.e. not enough fuel; usually associated with loss of power) can cause lean codes as well.
The last group of causes for these codes are bad combustion (i.e. too much unburnt air & fuel; usually associated with hesitation/surge and often caused by bad plugs/wires/coil(s)).
Good luck!
1999 Contour SE Sport MTX75 T-Red/Grey
Audio: Pioneer DEH-7400MP (MP3 CD), Pioneer TS-A6857 front & rear, PPI PCX-250, Infinity Perfect 10.1
Other: cup holders, cargo net, Blizzaks, Potenza RE950s
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